Speed and directional control in downhill skiing occurs by a skier shifting weight and applying lower leg force through the ball of the foot to the edge of the ski. Accurate and efficient edge control is required for clean turning and stopping. Conventional downhill ski boots include a substantially rigid thermoplastic outer boot that aids this force transmission, limiting medial and lateral flexion of the ankle, while also protecting the skier's ankle.
The rigid outer shell of a conventional ski boot receives an elastomeric foam lining. The lining both thermally insulates the skier's foot, and provides padding for comfort and fit between the skier's foot and the rigid outer shell of the boot. A series of over-center cam buckle straps are provided on the outer shell. The skier's foot is inserted downwardly into the boot, and the straps are then tightened in an attempt to compress the outer shell and the inner liner about the user's foot. Compression is limited, however, by the rigidity of the outer shell. After skiing, the buckles are loosened and the skier's foot is withdrawn upwardly from the boot. Due to the substantially rigid nature of the outer shell, withdrawal of the skier's foot can be difficult.
While conventional downhill ski boots provide adequate protection for a skier's foot, this construction is limited in the ability of the skier to closely conform the rigid outer shell and elastomeric inner lining about the skier's foot. Because the shape of a skier's foot varies from individual to individual, a ski boot tends to fit any given individual tightly in some areas of the foot and lower leg, and loosely in other areas. The ski boot is typically tightly compressed about the skier's shin, while it is inadequately tightened and fitted around other areas such as over the arch of the skier's foot. This is due primarily to the inability to adequately conform and compress the rigid outer shell.
As a result, certain areas of the skier's foot and lower leg receive too much pressure from a conventional ski boot, and may cause discomfort or pain to the skier, particularly during extended use. Likewise, the lack of close fit in other areas of the boot permits movement or slop of the skier's foot within the boot, such as horizontally in lateral and medial directions, during skiing. In order to shift the skier's weight to the ski through the boot, the skier's ball of the foot and toes will often first shift, resulting in less efficient force transmission and loss of a degree of control. Further, as a result of this loose fit, force tends to be applied from the skier's shin to the ski boot and then to the ski. This further increases the degree of pressure exerted on and discomfort to the forward side of the skier's shin.